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Proceedings Paper

In situ evaluation of a ship's shadow
Author(s): Christian T. Weir; David A. Siegel; Anthony F. Michaels; Dave W. Menzies
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Paper Abstract

In situ measurements of optical properties made from a ship can be biased by the ship's shadow. In an effort to evaluate the ship shadow perturbation created by the R/V Weatherbird II, profiles of downwelling irradiance, Ed(z,(lambda) ), upwelling radiance, Lu(z,(lambda) ), as well as derived apparent optical properties (AOPs) were obtained at distances of 1, 3, 6 and >= 20 m off the ship's stern. Two statistical analyses are explored here. The first compares the mean difference between simultaneously obtained fluxes and AOPs sampled at distances greater than 20 m from the ship to those taken 1 and 6 m off the stern. The second analysis compares derived AOPs taken at each of the four distances throughout the length of the experiment. Only rarely are significant differences found for data beyond three meters off the ship's stern; however at 1 m off the stern significant discrepancies are intermittently observed. This work illustrates that the inherent sources of noise in determining fluxes and AOPs in the upper ocean are generally greater than the effects incurred by the ship's own shadow under optimal conditions.

Paper Details

Date Published: 26 October 1994
PDF: 7 pages
Proc. SPIE 2258, Ocean Optics XII, (26 October 1994); doi: 10.1117/12.190130
Show Author Affiliations
Christian T. Weir, Univ. of California/Santa Barbara (United States)
David A. Siegel, Univ. of California/Santa Barbara (United States)
Anthony F. Michaels, Bermuda Biological Station for Research (Bermuda)
Dave W. Menzies, Univ. of California/Santa Barbara (United States)

Published in SPIE Proceedings Vol. 2258:
Ocean Optics XII
Jules S. Jaffe, Editor(s)

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